1. Field of the Invention
This invention relates generally to computer networking devices and more particularly to a robust packet arrival time detector using estimated signal power.
2. Description of the Background Art
Digital communication systems that communicate over a shared medium transmit information organized into discrete packets. To recover the information, a receiver must be able to determine when packets arrive, and to distinguish packets from noise. In general, the receiver must determine a Packet Arrival Time (PAT) for each received packet, since the packets might be transmitted from different asynchronous sources. The PAT is commonly used by sections of the receiver to prepare for the onset of the information-bearing portion of the packet. For example, an equalizer can use the PAT as an indicator of when to start training. In this situation, the more accurate the PAT, the faster the equalizer will converge before the onset of information, which makes the receiver less prone to packet errors.
A packet arrival time detector can be characterized by its detection and false alarm probabilities. These probabilities are dependent upon the value of a threshold for detection set by a designer of the detector. For example, a low value for the threshold increases the detection probability, but also increases the probability of a false alarm (false detection). Decreasing the sensitivity of the false alarm probability to the value of the threshold is a significant consideration of designers and manufacturers of digital communication systems.